The TFP index is computed as a ratio of total workload to total resource usage. Workload consists of three primary components: mail volume weighted by product type, miscellaneous output (e.g., passports) and delivery points. Weighted mail volume represents the largest share with 64.4 percent of the workload contribution in FY2013. Resource usage includes labor, materials and capital as its three primary inputs. Labor has the largest share with 75.6 percent of the resource usage weight in FY2013. The graph to the right identifies the most recent change over time in the TFP index. A graph depicting the trend since 1972 can be found in the Form 10-K filed by the Postal Service with the Postal Regulatory Commission on November 15, 2013 (see: www.prc.gov/Docs/88/88279/2013_USPS_%20FORM_10K_FINAL.pdf, page 44).